1. Field of the Invention
The present invention relates to a silver halide photographic light-sensitive material and, more particularly, to a high-sensitive, high-contrast, low-fog silver halide photographic light-sensitive material containing grains having a structure due to the difference in halogen compositions, wherein the grains are formed in the presence of an oxidizing agent capable of oxidizing silver. 2. Description of the Related Art
Basic properties required for a silver halide photographic light-sensitive material are high sensitivity, and low fog. High contrast is also an important property for the material. JP-A-60-143331 discloses a high sensitive silver halide emulsion having low-fog characteristic which contains layered grains, each grain consisting of a core having a high silver iodide content and an outermost shell having a silver iodide content lower than the core. (Hereinafter "JP-A" means Unexamined Published Japanese Patent Application.) These layered grains are desirable in terms of photographic sensitivity, but they have been found to have internal electron traps resulting from the structure due to the difference in the halogen compositions present in the internal portion of the grains. Further, these grains have been found to have disadvantages such as low contrast due to the internal traps.
Silver halide grains of another type are disclosed in U.S. Pat. Nos. 4,094,684, 4,142,900, 4,435,501, and 4,463,087. Each of these grains comprises a substrate grain having epitaxially grown portions different in the halogen composition. These grains are advantageous in terms of photographic sensitivity, but not in terms of contrast. This is because internal electron traps are formed at the interface between the substrate grain and the epitaxial portions as the epitaxial portions are gradually grown on the substrate grain.
JP-B-58-1410 discloses the technique of using both a reducing agent and an oxidizing agent while forming silver halide grains. (Hereinafter "JP-B" means Examined Published Japanese Patent Application.) Described as examples of the oxidizing agents are: iodine, potassium hexacyano ferrate (III), bromosuccinimide, p-quinone, and potassium periodate. This publication, however, is silent about the usefulness of the oxidizing agent when it is not used together with the reducing agent. Nor does the publication disclose any combination of grains having the internal structure with the oxidizing agent for silver. Further, JP-A-61-3136 also discloses the technique of using an oxidizing agent, such as hydrogen peroxide, while forming silver halide grains. However, this publication does not teach the advantageous effects derived from the combination of the grains having the structure with the oxidizing agent for silver.